Fired in CA for what was a common workplace practice

I was fired from my employment in California (working for a Temp agency) for falsifying time sheets. While this may be technically accurate, I was completing my timesheets in the same way that others also working for the Temp agency were and in a manner that I was taught by coworkers when I started the job at this site. There was a local pattern and practice for completing time sheets this way. I was the only person fired - others were given warnings. I have been denied unemployment benefits.

What are my chances with an appeal?

Well, I would think what if any of what you told me can be proven by you.

In other words, can you prove that you and others were doing the same thing and that only you were fired for it .. while others were just warned?

Or in unemployment terms .. did the employer choose to not uniformly enforce the consequences for time theft in just your case .. my thought is no you won't be able to do this.

But if you can prove that you had never been warned and that the employer's past or current behavior is to warn first .. then "possibly".

It also depends on the scope of the "technical error" and whether it caused harm to the employer and whether you understood that you were falsifying the timesheet .. or should have known that what you were doing was wrong to do.